1. Field of the Invention
The invention concerns a group control for elevators with double cars in which two cars are arranged in a common car frame. In particular, the elevator control includes car call memories and load weighing instruments assigned to the cars, floor call memories, selectors assigned to each elevator of the group indicating the floor of a possible stop, as well as a scanning device showing at least one position for every floor, whereby a control device is provided by means of which the double cars of the elevator group are allocatable to the floor calls.
Elevators of this type can transport twice as many passengers with every trip as do elevators with single cars. Since less stopping is necessary, the same quantity of floor calls can be served in less time, so that the carrying capacity can be increased considerably.
2. Description of the Prior Art
U.S. Pat. No. 3,625,311 discloses a control for an elevator group with double cars arranged in such a way that two adjacent floors can be served simultaneously. Thus, a building should be filled in as short as possible a time with approximately steady population of the double cars. On the ground floor the passengers going to even-numbered upper floors board the upper car, and those going to the odd-numbered upper floors board the lower car, whereby in each case the car call buttons for the floors not assigned to the car are disabled. As soon as the car must stop for a floor call, the disabling is removed, so that the person boarding can ride to a desired floor. The control of the elevator group operates according to a system of subdividing the path of travel into zones, whereby cars and zones are assigned to each other and the cars are distributed over the entire path of travel according to the location of the zones. With controls of this type, the allocation of the floor calls to the cars is solely dependent on the location and direction of the calls, whereas other factors, for example the car load, are not taken into consideration in the allocating procedure. An even distribution of passengers to the individual cars of the double cars is therefore not possible with normal operation of the elevator installation, so that optimum results are not attainable with regard to short average waiting times for passengers and to increased carrying capacity.
The allocation of the cars to the floor calls can be optimized, with respect to time, with a group control for elevators with single cars as disclosed in U.S. Pat. No. 4,355,705. A sum proportional to the time losses of waiting passengers and the time losses of the passengers in the car is calculated from the distance between the floor and the car position shown by a selector, the intermediate stops expected within this distance, and the momentary car load. The car load present in the computing time period is corrected for the probable boarders and persons getting off, derived from the numbers of persons getting on and off in the past, with respect to future intermediate stops. The calculations are performed by means of a computing device in the form of a microprocessor during a scanning cycle of each floor by a first scanner, whether a floor call is present or not. The lost time total, also called operating cost, is stored in a cost memory. During a cost comparison cycle by means of a second scanner, the operating costs of all elevators are compared with one another via a comparator device, whereby an allocation instruction is stored in an allocation memory of the elevator with the lowest operating costs. This instruction designates that floor to which the car in question is optimally assigned with respect to time.